Aeschi is a municipality in the district of Wasseramt in the canton of Solothurn in Switzerland. Burgäschisee is a lake in the forest on the …Aeschi is a municipality in the district of Wasseramt in the canton of Solothurn in Switzerland. Burgäschisee is a lake in the forest on the border with Seeberg. Aeschi has an area, as of 2009, of 3.8 square kilometers. Of this area, 2.4 km² or 63.2% is used for agricultural purposes, while 0.66 km² or 17.4% is forested. Of the rest of the land, 0.55 km² or 14.5% is settled, 0.16 km² or 4.2% is either rivers or lakes and 0.04 km² or 1.1% is unproductive land. After the 2012 merger, the area increased to 5.4 square kilometers.